The invention relates to novel compounds that function as protein tyrosine kinase inhibitors. The family of 5-oxo-5,8-dihydro-pyrido-pyrimidines has exhibited promising pharmaceutical properties in the past; U.S. Pat. No. 4,556,709, JP 09221424 and DE 19532235 are indicative of recent investigations. More particularly, the invention relates to novel compounds that function as inhibitors of c-fms kinase.
c-Fms is a type III receptor tyrosine kinase selectively expressed on macrophages and their progenitors. The extracellular Ig domain of c-fms binds macrophage colony stimulating factor (M-CSF), also known as colony stimulating factor-1 (CSF-1). Binding of CSF-1 induces receptor dimerization and trans-phosphorylation of the intracellular c-fms kinase domain on Y723 and other tyrosine residues. Once phosphorylated, c-fms efficiently phosphorylates several cytoplasmic signaling molecules that lead to de novo gene expression and proliferation. Small molecule inhibitors of the kinase catalytic site of c-fms are expected to prevent CSF-1 induced cellular responses.
Macrophages are a predominant source of tumor necrosis factor (TNF) and interleukin-1 (IL-1) in the destructive pannus of rheumatoid arthritis. TNF and IL-1 activate stromal expression of hematopoietic factors including CSF-1. In turn, CSF-1 recruits monocytes and promotes macrophage survival, functional activation, and in some settings, proliferation. Thus, TNF and CSF-1 interact in a perpetuating cycle that leads to inflammation and joint destruction. The exclusive receptor for CSF-1 is c-fms, and the disclosed invention is a c-fms inhibitor designed to interrupt this cycle.
Macrophages are abundant at sites of chronic inflammation where they are are often the most important source of TNF, IL-1, and other cytokines. Moreover, macrophages can be an important source of factors that function in tissue remodeling such as plasminogen activators, matrix metalloproteases, vascular endothelial growth factor, and transforming growth factor-β. The numbers of macrophages present within target tissues have strongly correlated with disease severity in rheumatoid arthritis (Ann Rheum Dis 53 (1994) pp 39-44), immune nephritis (Kidney Int 54 (1998) pp 143-151), and graft rejection (Transpl Int 7 Suppl 1 (1994) pp 577-579). Macrophage numbers are also elevated in atherosclerotic plaque (Arch Pathol Lab Med 109 (1985) pp 445-449), adipose tissue in obesity (J Clin Invest 112 (2003) pp 1796-1898), diabetic nephropathy (Kidney Int 65 (2004) pp 116-128), cardiac hypertrophy (Hypertension 25 (1999) pp 132-138), and in many solid tumors (Trends in Immunology 23 (2002) pp 549-555), particularly breast cancer (J. Experimental Medicine 193 (2001) pp 727-739), where they are thought to contribute to disease progression. Modulation of macrophage function through inhibition of c-fms thus is expected to be useful in treating inflammatory mediated diseases and conditions.
Another example of the invention is the use of any of the compounds described herein in the preparation of a medicament for treating: rheumatoid arthritis, graft rejection, atherosclerosis, obesity, diabetic nephropathy, cardiac hypertrophy and solid tumor diseases, especially breast cancer, in a subject in need of such treatment.
Preclinical data suggest CSF-1/FMS is a particularly viable therapeutic target for rheumatoid arthritis. Recent work has shown that neutralizing antibodies to CSF-1 reduce substantially the severity of collagen-induced arthritis in mice (J Leukoc Biol 68 (2000) pp 144-150). The authors additionally demonstrated that recombinant CSF-1 exacerbated the disease progress in this model. Therefore, a preferred use for the invention is the treatment of rheumatoid arthritis.